UNIT 6: THERMODYNAMICS EXAM STUDY GUIDE

UNIT 6: THERMODYNAMICS
–

EXAM STUDY GUIDE


6.1
–

Methods of Heat Transfer

Give examples of conduction, convection, and radiation. How can you tell these three apart?

6.1, 6.2, 6.3 Quiz
–

Multiple choice questions

6.1 Homework

–

All questions

6.1 and

6.2 Exit Ticket:
#1, 2, 8


Conduction

–

heat transferred through a solid (movement of electrons)

Convection
–

heat transferred through a liquid or gas (expansion and circulation of molecules relating to density)

Radiation

–

heat transferred as a wave (e.g
. heat emitted from sun, fires, lightbulbs, microwaves)


6.2
–

Laws of Thermodynamics

What are the three laws of thermodynamics?


1
st

–

Law of Conservation of Energy



Examples?


6.1, 6.2, 6.3 Quiz

–

fill in the blank (3 laws question #4), Short Answer #2



2
nd

–

Law of Entropy


Examples?

6.1, 6.2, 6.3 Quiz

–

fill in the blank (3 laws questions #1, 2)

6.1 and 6.2 Exit Ticket
-

#5, 7

6.2 HW
-

#2,3,4,5


3
rd

–

Third Law (nothing can reach absolute zero)


Examples?


6.1, 6.2, 6.3 Quiz
–

fill in the blank (3
laws question#3), Short Answer #1


Applications of the 1
st

Law:







When is heat positive? Negative?

+
: absorbed

-
: released


When is work positive? Negative?

+:

something else does work
on

system

-
: system does work, work done
by

system



Example
problems? [Get from notes / quizzes]

6.1, 6.2, 6.3 Quiz:

Short Answer #3

Bellringer
#6
-
8

6.2 HW:

#1
, 8a*(includes W = mg
Δ
h from unit 5)

6.1 and 6.2 Exit Ticket:

#3






Heat Engines

Multiple processes:

1)

Absorbs heat

2)

Engine does work (releases energy)

3)

Engine

releases heat


Picture:

*Drawn in Class*
















*NOTE: These equations for heat engines
NOT

provided on your exam!!!


Examples:

6.1, 6.2, 6.3 Quiz:

Short Answer #4a

6.1 and 6.2 Exit Ticket:
#4, 6 (first step of
2
-
step problem)

6.2 HW:

#6


Efficiency:











***NOTE: equations
NOT

provided on your exam!!!

6.1, 6.2, 6.3 Quiz:

Short Answer #4b, 5

6.1 and 6.2 Exit Ticket:

#6 (second step of 2
-
step problem)

6.2 HW:

#7, 8b, 9*(includes W = Fd

from Unit 5)


6.3
–

Energetic Properties of Matter

Rank the phases in order of increasing:


Potential Energy?

***WILL NOT BE ON EXAM


䥮 covering thi猠in cla獳s 䤠獴ated 獯lid猠= high 偅 and ga獥猠=
low 偅; however, after di獣u獳son猠with 獴udent猠who we
re confu獥d about adding 偅 on heating curve猬 䤠clarified
that 獯lid猠have the mo獴
negative

potential energy because of intermolecular force attractions, while ideal gases are
assumed to have have
zero

potential energy due to no intermolecular force att
ractions. Because of this, students
were confused since technically, solids still have less PE than liquids or gases. As a result, I w
ill

discuss and clarify in
class on Monday
after

the exam and will not test you on this topic. If, after you’ve mastered a
ll other material in this
unit, you’d like to further investigate this topic yourself with visuals, please consult
http://hyperphysics.phy
-
astr.gsu.edu/hbase/hframe.html
***




Kinetic E
nergy?

(low) Solids


Liquids


Gases (high)



Entropy?

(low) Solids


Liquids


Gases (high)


Draw and label a heating curve. Label phases and phase transitions, where KE is increasing, and where PE is increasing.


Legs A, C, E: increasing KE. Legs B,
D: increasing PE


Practice Problems:
6.3 HW sheet that says “Chemistry” on it



6.1, 6.2, 6.3 Quiz:
Fill in the blank up until the question about boiling point

6.4
–

Specific Heat, Thermal Equilibrium, and Latent Heat

Important about specific heat:

High sp
ecific heat requires more energy to change temperature (will have less
Δ
T)





Low specific heat requires less energy to change temperature (will have greater
Δ
T)





On a graph, high c
p

=
small slope; low c
p

= large slope


What equation do you use when
temperature is changing?










Examples:

6.4 Quiz:
#1, 2, 3a




6.4.1 Exit Ticket and Homework:

All problems


What equation do you use when phase is changing?







Examples:

6.4.3 Homework:
#1,2


How do you find these on a graph?

1)

Determin
e leg of phase change on graph

2)

Q = (Final heat absorbed on leg)
–

(Initial heat absorbed on leg); complete conversion to J if necessary

3)

Plug into Q = mL to solve for L



Examples:

6.4.3 Homework:
#3,4



6.4 Quiz:

3b


When two substances are mixed, what equ
ation do you use?


(




)



(




)



*NOTE: This equation will not be given to you!



Examples:

6.4.2 Homework:

All problems




6.4 Quiz:

#4



ADDITIONAL PROBLEMS TO WORK:
Problems involving both phase change
AND

temperature change

1)

ID phases present and temperatures for each phase (separated by melting/boiling point)

2)

Calculate Q = mc
p
Δ
T for each phase

3)

Calculate Q = mL for each phase change

4)

Sum all Qs to obtain your total heat. Solve for unknown.


Examples:

6.4.
3 HW:

#
5,6,7


6.4 Quiz:

#5